Full definition
An enclosed heavy-duty mixing machine with two counter-rotating rotors (tangential Banbury-type or intermeshing type) inside a temperature-controlled chamber, used for intensive mixing of rubber compounds at high shear and controlled temperature. The Banbury mixer — named after inventor Fernley H. Banbury (1916 patent) — revolutionized rubber manufacturing by replacing slow, labor-intensive open-mill mixing with a fast, repeatable batch process. Specifications: chamber volumes 1.5-650 liters (lab to production), rotor speed 20-80 RPM, ram pressure 3-8 bar, temperature control via cooling water in rotors, chamber, and door. Mixing cycle: 3-8 minutes per batch. The ram (floating weight) presses the rubber charge against the rotors and chamber walls for intensive mixing. Power consumption: 300-1,500 kW for large production units. Temperature monitoring is critical — excessive heat degrades the polymer or causes premature scorch. Typically a two-stage process: stage 1 (non-productive — polymer, fillers, oils, protectants at high temperature) and stage 2 (productive — curatives added at lower temperature on a mill or in a second pass). Manufacturers: Farrel Pomini, HF Mixing Group, Kobelco, Pelmar. Per standard rubber manufacturing practice.